Dog studies will be performed which will examine pulmonary capillary permeability and water content in animal models of pulmonary edema and acute respiratory failure. The studies will utilize new analysis methods developed over the past two years from indicator dilution data. In parallel with the dog studies, data will be obtained from two patient groups. One group will consist of patients in acute respiratory failure or pulmonary edema. These patients will be followed on a daily basis to recovery or death. The second group of patients will include adults scheduled for thoracotomy and pulmonary resection. In these patients we will correlate the in vivo measurements of lung water with the actual water content of the lung removal at surgery.